1. Field of the Invention
The present invention relates generally to bicycle suspension systems and frame assemblies. In particular, the present invention relates to configurations for rear suspension assemblies and mounting arrangements for rear suspension assemblies suitable for use in connection with off-road bicycles.
2. Description of the Related Art
Off-road bicycles, or mountain bikes, may be equipped with front and rear suspension assemblies operably positioned between the frame of the bicycle and the front and rear wheels, respectively. Providing front and rear suspension on a mountain bike potentially improves handling and performance by absorbing bumps, and other rough trail conditions, which may be encountered while riding off-road. However, because mountain bikes are typically pedal-driven, i.e., use the rider's power output to propel the bicycle, the provision of rear suspension, especially, may undesirably absorb a rider's power output, resulting in wasted effort.
Accordingly, rear suspension systems commonly incorporated on engine-driven vehicles, such as motorcycles, have proven undesirable for use with pedal-driven vehicles, such as mountain bikes. In addition, because a mountain bike is propelled solely by power output from the rider, it is desirable that the rear suspension assembly be lightweight. Rear suspension systems of engine-driven vehicles commonly emphasize strength over weight and, therefore, have not been widely incorporated on mountain bikes.
Mountain bike rear suspension designs, utilizing multiple linkage members, are currently used and are often effective at isolating pedal-induced and brake-induced forces from acting on the rear suspension. However, one problem associated with prior mountain bike rear suspension designs involves placement of the rear shock absorber. Due to the relatively complex nature of common mountain bike rear suspension assemblies, the placement of the rear shock absorber has often precluded the use of a traditional triangular main frame of the mountain bike.
A common rear suspension arrangement for a bicycle frame assembly includes an articulating sub-frame having a lever assembly or link that couples a portion of the sub-frame to a main frame of the bicycle frame assembly. The link may also support one end of a shock absorber operably coupled between the main frame and the sub-frame. The link often includes a pair of lever arms, which are spaced from one another in a lateral direction and interconnected by a crossbar portion such that the lever arms move together as a unit. However, a disadvantage of such an arrangement is that a clearance space must be provided to accommodate the crossbar portion throughout the range of movement of the link during articulation of the sub-frame. Such an arrangement can place limitations on the design of the remainder of the frame assembly. For example, sometimes the seat tube is provided in two distinct portions with an interrupted intermediate section, which provides a clearance space to accommodate movement of the link. As another example, the rear shock may be positioned within the internal space defined by the main frame and the movement of the link may also take place within this space, thereby limiting the availability of this space for other purposes.